/* This file is part of the Palabos library.
 *
 * The Palabos softare is developed since 2011 by FlowKit-Numeca Group Sarl
 * (Switzerland) and the University of Geneva (Switzerland), which jointly
 * own the IP rights for most of the code base. Since October 2019, the
 * Palabos project is maintained by the University of Geneva and accepts
 * source code contributions from the community.
 *
 * Contact:
 * Jonas Latt
 * Computer Science Department
 * University of Geneva
 * 7 Route de Drize
 * 1227 Carouge, Switzerland
 * jonas.latt@unige.ch
 *
 * The most recent release of Palabos can be downloaded at
 * <https://palabos.unige.ch/>
 *
 * The library Palabos is free software: you can redistribute it and/or
 * modify it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * The library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/** \file
 * Helper functions for the implementation of non-Newtonian Carreau
 * dynamics.
 */
#ifndef CARREAU_DYNAMICS_TEMPLATES_H
#define CARREAU_DYNAMICS_TEMPLATES_H

#include "core/util.h"

namespace plb {

template <typename T, int N>
struct ImplicitOmega {
    T operator()(T alpha, T nu0_nuInfOverCs2, T nuInfOverCs2, T nMinusOneOverTwo, T omega0)
    {
        ImplicitOmega<T, N - 1> omega;
        T omSqr = omega(alpha, nu0_nuInfOverCs2, nuInfOverCs2, nMinusOneOverTwo, omega0);
        omSqr *= omSqr;

        return (T)2
               / ((T)1 + (T)2 * nu0_nuInfOverCs2 * std::pow((T)1 + alpha * omSqr, nMinusOneOverTwo)
                  + (T)2 * nuInfOverCs2);
    }
};

template <typename T>
struct ImplicitOmega<T, 0> {
    T operator()(T alpha, T nu0_nuInfOverCs2, T nuInfOverCs2, T nMinusOneOverTwo, T omega0)
    {
        return (T)2
               / ((T)1
                  + (T)2 * nu0_nuInfOverCs2
                        * std::pow((T)1 + alpha * omega0 * omega0, nMinusOneOverTwo)
                  + (T)2 * nuInfOverCs2);
    }
};

/// This structure forwards the calls to the appropriate helper class
template <typename T, int N>
struct carreauDynamicsTemplates {
    static T fromPiAndRhoToOmega(
        T alpha, T nu0_nuInfOverCs2, T nuInfOverCs2, T nMinusOneOverTwo, T omega0)
    {
        ImplicitOmega<T, N> omega;

        return omega(alpha, nu0_nuInfOverCs2, nuInfOverCs2, nMinusOneOverTwo, omega0);
    }

};  // struct carreauDynamicsTemplates

}  // namespace plb

#endif  // CARREAU_DYNAMICS_TEMPLATES_H
